Lower-Luminosity Obscured AGN Host Galaxies are Not Predominantly in Major-Merging Systems at Cosmic Noon

Abstract

For over 60 years, the scientific community has studied actively growing central super-massive black holes (active galactic nuclei -- AGN) but fundamental questions on their genesis remain unanswered. Numerical simulations and theoretical arguments show that black hole growth occurs during short-lived periods ($\sim$ 10${}^7$ -10${}^8$ yr) of powerful accretion. Major mergers are commonly invoked as the most likely dissipative process to trigger the rapid fueling of AGN. If the AGN-merger paradigm is true, we expect galaxy mergers to coincide with black hole accretion during a heavily obscured AGN phase (N${}_H$ $>10^{23}$ cm${}^{-2}$). Starting from one of the largest samples of obscured AGN at 0.5 $<$ $z$ $<$ 3.1, we select 40 non-starbursting lower-luminosity obscured AGN. We then construct a one-to-one matched redshift- and near-IR magnitude-matched non-starbursting inactive galaxy control sample. Combining deep color \textit{Hubble Space Telescope} imaging and a novel method of human classification, we test the merger-AGN paradigm prediction that heavily obscured AGN are strongly associated with galaxies undergoing a major merger. On the total sample of 80 galaxies, we estimate each individual classifier's accuracy at identifying merging galaxies/post-merging systems and isolated galaxies. We calculate the probability of each galaxy being in either a major merger or isolated system, given the accuracy of the human classifiers and the individual classifications of each galaxy. We do not find statistically significant evidence that obscured AGN at cosmic noon are predominately found in systems with evidence of significant merging/post-merging features.

19 pages, 11 figures, accepted in ApJ

References in corpus (21)

• A Cosmological Framework for the Co-Evolution of Quasars, Supermassive Black Holes, and Elliptical Galaxies: I. Galaxy Mergers & Quasar Activity
• The Co-Evolution of Galaxies and Supermassive Black Holes: Insights from Surveys of the Contemporary Universe
• An ultra-deep near-infrared spectrum of a compact quiescent galaxy at z=2.2
• 3D-HST WFC3-selected Photometric Catalogs in the Five CANDELS/3D-HST Fields: Photometry, Photometric Redshifts and Stellar Masses
• The synthesis of the cosmic X-ray background in the Chandra and XMM-Newton era
• The Herschel view of the dominant mode of galaxy growth from z=4 to the present day
• The Chandra Deep Field-South Survey: 7 Ms Source Catalogs
• Fueling Low-Level AGN Activity Through the Stochastic Accretion of Cold Gas
• Evidence for Quasar Activity Triggered by Galaxy Mergers in HST Observations of Dust-reddened Quasars
• A definitive merger-AGN connection at z~0 with CFIS: mergers have an excess of AGN and AGN hosts are more frequently disturbed
• Merging and Clustering of the Swift BAT AGN Sample
• HST WFC3/IR Observations of Active Galactic Nucleus Host Galaxies at z~2: Supermassive Black Holes Grow in Disk Galaxies
• Interacting galaxies on FIRE-2: The connection between enhanced star formation and interstellar gas content
• The X-Ray to Mid-Infrared Relation of AGN at High Luminosity
• Host galaxies of luminous z$\sim$0.6 quasars: Major mergers are not prevalent at the highest AGN luminosities
• Galaxy And Mass Assembly (GAMA): the effect of close interactions on star formation in galaxies
• Diverse Structural Evolution at z > 1 in Cosmologically Simulated Galaxies
• The host galaxies of X-ray selected Active Galactic Nuclei to z=2.5: Structure, star-formation and their relationships from CANDELS and Herschel/PACS
• Distinguishing Mergers and Disks in High Redshift Observations of Galaxy Kinematics
• The X-ray emission of z>2.5 active galactic nuclei can be obscured by their host galaxies
• The spatially resolved star formation history of mergers: A comparative study of the LIRGs IC1623, NGC6090, NGC2623, and Mice

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